In vivo confocal microscopy imaging of the cornea will be performed before lens wear and at 3 and 6 months post lens wear by one masked examiner on all subjects at National Taiwan University. One drop of 0.5% proparacaine solution and artificial tears was instilled immediately before each exam. After asking the patients to look straight ahead, an in vivo confocal microscope (Confoscan 3.4.1; Nidek Technologies, Padova, Italy) equipped with a standard 40x water-immersion front lens captured images of the full thickness of the central cornea automatically. Each examination took approximately 1 to 3 minutes and recorded 350 images at a distance of 1.5 and 4 μm on the z-axis between successive images. During each visit, measurements were repeated with 4 um z-interval for 3 times followed by 1.5 um z-interval for 3 times. Analysis of epithelial cells morphology, epithelial thickness, and stromal reaction follows that has been published by Chen et al22-24. Corneal nerve morphology and density will also be recorded and analyzed.